I have been researching this on amazon and other places- some of the more expensive ones say they have advanced features? what does that mean? what does a $400 one do that a $40 doesn’t? Unless i can hit a button the $400 one and it actually fixes the problem, otherwise, i can only imagine it has more codes for complex issues?
The $400 one can probably do more complex things, like crankshaft/camshaft position sensor re-learn, etc… it will also be able to show data the simple scanner can’t access. Things like fuel trim, a/f ratios, engine temp, trans temp, misfire counts and hundreds more. If you just need codes read, $40 one is fine. If you want to actually diagnose problems, $400 one is needed.